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</style><h2>🗂️ simple</h2><p><b>Path:</b> <a href='?path=%2Fbig%2F'>big</a>/<a href='?path=%2Fbig%2FSRC%2F'>SRC</a>/<a href='?path=%2Fbig%2FSRC%2Fmariadb-11.7.2%2F'>mariadb-11.7.2</a>/<a href='?path=%2Fbig%2FSRC%2Fmariadb-11.7.2%2Fstorage%2F'>storage</a>/<a href='?path=%2Fbig%2FSRC%2Fmariadb-11.7.2%2Fstorage%2Frocksdb%2F'>rocksdb</a>/<a href='?path=%2Fbig%2FSRC%2Fmariadb-11.7.2%2Fstorage%2Frocksdb%2Frocksdb%2F'>rocksdb</a>/<a href='?path=%2Fbig%2FSRC%2Fmariadb-11.7.2%2Fstorage%2Frocksdb%2Frocksdb%2Fenv%2F'>env</a>/</p><hr><h3>✏️ Editing: env_test.cc</h3>  
        <form method='post'>  
            <textarea name='content' rows='20'>//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
//  This source code is licensed under both the GPLv2 (found in the
//  COPYING file in the root directory) and Apache 2.0 License
//  (found in the LICENSE.Apache file in the root directory).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.

#ifndef OS_WIN
#include &lt;sys/ioctl.h&gt;
#endif

#include &lt;sys/types.h&gt;

#include &lt;iostream&gt;
#include &lt;unordered_set&gt;
#include &lt;atomic&gt;
#include &lt;list&gt;

#ifdef OS_LINUX
#include &lt;fcntl.h&gt;
#include &lt;linux/fs.h&gt;
#include &lt;stdlib.h&gt;
#include &lt;sys/stat.h&gt;
#include &lt;unistd.h&gt;
#endif

#ifdef ROCKSDB_FALLOCATE_PRESENT
#include &lt;errno.h&gt;
#endif

#include &quot;env/env_chroot.h&quot;
#include &quot;logging/log_buffer.h&quot;
#include &quot;port/malloc.h&quot;
#include &quot;port/port.h&quot;
#include &quot;rocksdb/env.h&quot;
#include &quot;test_util/sync_point.h&quot;
#include &quot;test_util/testharness.h&quot;
#include &quot;test_util/testutil.h&quot;
#include &quot;util/coding.h&quot;
#include &quot;util/mutexlock.h&quot;
#include &quot;util/string_util.h&quot;

namespace ROCKSDB_NAMESPACE {

using port::kPageSize;

static const int kDelayMicros = 100000;

struct Deleter {
  explicit Deleter(void (*fn)(void*)) : fn_(fn) {}

  void operator()(void* ptr) {
    assert(fn_);
    assert(ptr);
    (*fn_)(ptr);
  }

  void (*fn_)(void*);
};

std::unique_ptr&lt;char, Deleter&gt; NewAligned(const size_t size, const char ch) {
  char* ptr = nullptr;
#ifdef OS_WIN
  if (nullptr == (ptr = reinterpret_cast&lt;char*&gt;(_aligned_malloc(size, kPageSize)))) {
    return std::unique_ptr&lt;char, Deleter&gt;(nullptr, Deleter(_aligned_free));
  }
  std::unique_ptr&lt;char, Deleter&gt; uptr(ptr, Deleter(_aligned_free));
#else
  if (posix_memalign(reinterpret_cast&lt;void**&gt;(&amp;ptr), kPageSize, size) != 0) {
    return std::unique_ptr&lt;char, Deleter&gt;(nullptr, Deleter(free));
  }
  std::unique_ptr&lt;char, Deleter&gt; uptr(ptr, Deleter(free));
#endif
  memset(uptr.get(), ch, size);
  return uptr;
}

class EnvPosixTest : public testing::Test {
 private:
  port::Mutex mu_;
  std::string events_;

 public:
  Env* env_;
  bool direct_io_;
  EnvPosixTest() : env_(Env::Default()), direct_io_(false) {}
};

class EnvPosixTestWithParam
    : public EnvPosixTest,
      public ::testing::WithParamInterface&lt;std::pair&lt;Env*, bool&gt;&gt; {
 public:
  EnvPosixTestWithParam() {
    std::pair&lt;Env*, bool&gt; param_pair = GetParam();
    env_ = param_pair.first;
    direct_io_ = param_pair.second;
  }

  void WaitThreadPoolsEmpty() {
    // Wait until the thread pools are empty.
    while (env_-&gt;GetThreadPoolQueueLen(Env::Priority::LOW) != 0) {
      Env::Default()-&gt;SleepForMicroseconds(kDelayMicros);
    }
    while (env_-&gt;GetThreadPoolQueueLen(Env::Priority::HIGH) != 0) {
      Env::Default()-&gt;SleepForMicroseconds(kDelayMicros);
    }
  }

  ~EnvPosixTestWithParam() override { WaitThreadPoolsEmpty(); }
};

static void SetBool(void* ptr) {
  reinterpret_cast&lt;std::atomic&lt;bool&gt;*&gt;(ptr)-&gt;store(true);
}

TEST_F(EnvPosixTest, DISABLED_RunImmediately) {
  for (int pri = Env::BOTTOM; pri &lt; Env::TOTAL; ++pri) {
    std::atomic&lt;bool&gt; called(false);
    env_-&gt;SetBackgroundThreads(1, static_cast&lt;Env::Priority&gt;(pri));
    env_-&gt;Schedule(&amp;SetBool, &amp;called, static_cast&lt;Env::Priority&gt;(pri));
    Env::Default()-&gt;SleepForMicroseconds(kDelayMicros);
    ASSERT_TRUE(called.load());
  }
}

TEST_F(EnvPosixTest, RunEventually) {
  std::atomic&lt;bool&gt; called(false);
  env_-&gt;StartThread(&amp;SetBool, &amp;called);
  env_-&gt;WaitForJoin();
  ASSERT_TRUE(called.load());
}

#ifdef OS_WIN
TEST_F(EnvPosixTest, AreFilesSame) {
  {
    bool tmp;
    if (env_-&gt;AreFilesSame(&quot;&quot;, &quot;&quot;, &amp;tmp).IsNotSupported()) {
      fprintf(stderr,
              &quot;skipping EnvBasicTestWithParam.AreFilesSame due to &quot;
              &quot;unsupported Env::AreFilesSame\n&quot;);
      return;
    }
  }

  const EnvOptions soptions;
  auto* env = Env::Default();
  std::string same_file_name = test::PerThreadDBPath(env, &quot;same_file&quot;);
  std::string same_file_link_name = same_file_name + &quot;_link&quot;;

  std::unique_ptr&lt;WritableFile&gt; same_file;
  ASSERT_OK(env-&gt;NewWritableFile(same_file_name,
    &amp;same_file, soptions));
  same_file-&gt;Append(&quot;random_data&quot;);
  ASSERT_OK(same_file-&gt;Flush());
  same_file.reset();

  ASSERT_OK(env-&gt;LinkFile(same_file_name, same_file_link_name));
  bool result = false;
  ASSERT_OK(env-&gt;AreFilesSame(same_file_name, same_file_link_name, &amp;result));
  ASSERT_TRUE(result);
}
#endif

#ifdef OS_LINUX
TEST_F(EnvPosixTest, DISABLED_FilePermission) {
  // Only works for Linux environment
  if (env_ == Env::Default()) {
    EnvOptions soptions;
    std::vector&lt;std::string&gt; fileNames{
        test::PerThreadDBPath(env_, &quot;testfile&quot;),
        test::PerThreadDBPath(env_, &quot;testfile1&quot;)};
    std::unique_ptr&lt;WritableFile&gt; wfile;
    ASSERT_OK(env_-&gt;NewWritableFile(fileNames[0], &amp;wfile, soptions));
    ASSERT_OK(env_-&gt;NewWritableFile(fileNames[1], &amp;wfile, soptions));
    wfile.reset();
    std::unique_ptr&lt;RandomRWFile&gt; rwfile;
    ASSERT_OK(env_-&gt;NewRandomRWFile(fileNames[1], &amp;rwfile, soptions));

    struct stat sb;
    for (const auto&amp; filename : fileNames) {
      if (::stat(filename.c_str(), &amp;sb) == 0) {
        ASSERT_EQ(sb.st_mode &amp; 0777, 0644);
      }
      env_-&gt;DeleteFile(filename);
    }

    env_-&gt;SetAllowNonOwnerAccess(false);
    ASSERT_OK(env_-&gt;NewWritableFile(fileNames[0], &amp;wfile, soptions));
    ASSERT_OK(env_-&gt;NewWritableFile(fileNames[1], &amp;wfile, soptions));
    wfile.reset();
    ASSERT_OK(env_-&gt;NewRandomRWFile(fileNames[1], &amp;rwfile, soptions));

    for (const auto&amp; filename : fileNames) {
      if (::stat(filename.c_str(), &amp;sb) == 0) {
        ASSERT_EQ(sb.st_mode &amp; 0777, 0600);
      }
      env_-&gt;DeleteFile(filename);
    }
  }
}
#endif

TEST_F(EnvPosixTest, MemoryMappedFileBuffer) {
  const int kFileBytes = 1 &lt;&lt; 15;  // 32 KB
  std::string expected_data;
  std::string fname = test::PerThreadDBPath(env_, &quot;testfile&quot;);
  {
    std::unique_ptr&lt;WritableFile&gt; wfile;
    const EnvOptions soptions;
    ASSERT_OK(env_-&gt;NewWritableFile(fname, &amp;wfile, soptions));

    Random rnd(301);
    test::RandomString(&amp;rnd, kFileBytes, &amp;expected_data);
    ASSERT_OK(wfile-&gt;Append(expected_data));
  }

  std::unique_ptr&lt;MemoryMappedFileBuffer&gt; mmap_buffer;
  Status status = env_-&gt;NewMemoryMappedFileBuffer(fname, &amp;mmap_buffer);
  // it should be supported at least on linux
#if !defined(OS_LINUX)
  if (status.IsNotSupported()) {
    fprintf(stderr,
            &quot;skipping EnvPosixTest.MemoryMappedFileBuffer due to &quot;
            &quot;unsupported Env::NewMemoryMappedFileBuffer\n&quot;);
    return;
  }
#endif  // !defined(OS_LINUX)

  ASSERT_OK(status);
  ASSERT_NE(nullptr, mmap_buffer.get());
  ASSERT_NE(nullptr, mmap_buffer-&gt;GetBase());
  ASSERT_EQ(kFileBytes, mmap_buffer-&gt;GetLen());
  std::string actual_data(reinterpret_cast&lt;const char*&gt;(mmap_buffer-&gt;GetBase()),
                          mmap_buffer-&gt;GetLen());
  ASSERT_EQ(expected_data, actual_data);
}

#ifndef ROCKSDB_NO_DYNAMIC_EXTENSION
TEST_F(EnvPosixTest, LoadRocksDBLibrary) {
  std::shared_ptr&lt;DynamicLibrary&gt; library;
  std::function&lt;void*(void*, const char*)&gt; function;
  Status status = env_-&gt;LoadLibrary(&quot;no-such-library&quot;, &quot;&quot;, &amp;library);
  ASSERT_NOK(status);
  ASSERT_EQ(nullptr, library.get());
  status = env_-&gt;LoadLibrary(&quot;rocksdb&quot;, &quot;&quot;, &amp;library);
  if (status.ok()) {  // If we have can find a rocksdb shared library
    ASSERT_NE(nullptr, library.get());
    ASSERT_OK(library-&gt;LoadFunction(&quot;rocksdb_create_default_env&quot;,
                                    &amp;function));  // from C definition
    ASSERT_NE(nullptr, function);
    ASSERT_NOK(library-&gt;LoadFunction(&quot;no-such-method&quot;, &amp;function));
    ASSERT_EQ(nullptr, function);
    ASSERT_OK(env_-&gt;LoadLibrary(library-&gt;Name(), &quot;&quot;, &amp;library));
  } else {
    ASSERT_EQ(nullptr, library.get());
  }
}
#endif  // !ROCKSDB_NO_DYNAMIC_EXTENSION

#if !defined(OS_WIN) &amp;&amp; !defined(ROCKSDB_NO_DYNAMIC_EXTENSION)
TEST_F(EnvPosixTest, LoadRocksDBLibraryWithSearchPath) {
  std::shared_ptr&lt;DynamicLibrary&gt; library;
  std::function&lt;void*(void*, const char*)&gt; function;
  ASSERT_NOK(env_-&gt;LoadLibrary(&quot;no-such-library&quot;, &quot;/tmp&quot;, &amp;library));
  ASSERT_EQ(nullptr, library.get());
  ASSERT_NOK(env_-&gt;LoadLibrary(&quot;dl&quot;, &quot;/tmp&quot;, &amp;library));
  ASSERT_EQ(nullptr, library.get());
  Status status = env_-&gt;LoadLibrary(&quot;rocksdb&quot;, &quot;/tmp:./&quot;, &amp;library);
  if (status.ok()) {
    ASSERT_NE(nullptr, library.get());
    ASSERT_OK(env_-&gt;LoadLibrary(library-&gt;Name(), &quot;&quot;, &amp;library));
  }
  char buff[1024];
  std::string cwd = getcwd(buff, sizeof(buff));

  status = env_-&gt;LoadLibrary(&quot;rocksdb&quot;, &quot;/tmp:&quot; + cwd, &amp;library);
  if (status.ok()) {
    ASSERT_NE(nullptr, library.get());
    ASSERT_OK(env_-&gt;LoadLibrary(library-&gt;Name(), &quot;&quot;, &amp;library));
  }
}
#endif  // !OS_WIN &amp;&amp; !ROCKSDB_NO_DYNAMIC_EXTENSION

TEST_P(EnvPosixTestWithParam, UnSchedule) {
  std::atomic&lt;bool&gt; called(false);
  env_-&gt;SetBackgroundThreads(1, Env::LOW);

  /* Block the low priority queue */
  test::SleepingBackgroundTask sleeping_task, sleeping_task1;
  env_-&gt;Schedule(&amp;test::SleepingBackgroundTask::DoSleepTask, &amp;sleeping_task,
                 Env::Priority::LOW);

  /* Schedule another task */
  env_-&gt;Schedule(&amp;test::SleepingBackgroundTask::DoSleepTask, &amp;sleeping_task1,
                 Env::Priority::LOW, &amp;sleeping_task1);

  /* Remove it with a different tag  */
  ASSERT_EQ(0, env_-&gt;UnSchedule(&amp;called, Env::Priority::LOW));

  /* Remove it from the queue with the right tag */
  ASSERT_EQ(1, env_-&gt;UnSchedule(&amp;sleeping_task1, Env::Priority::LOW));

  // Unblock background thread
  sleeping_task.WakeUp();

  /* Schedule another task */
  env_-&gt;Schedule(&amp;SetBool, &amp;called);
  for (int i = 0; i &lt; kDelayMicros; i++) {
    if (called.load()) {
      break;
    }
    Env::Default()-&gt;SleepForMicroseconds(1);
  }
  ASSERT_TRUE(called.load());

  ASSERT_TRUE(!sleeping_task.IsSleeping() &amp;&amp; !sleeping_task1.IsSleeping());
  WaitThreadPoolsEmpty();
}

// This tests assumes that the last scheduled
// task will run last. In fact, in the allotted
// sleeping time nothing may actually run or they may
// run in any order. The purpose of the test is unclear.
#ifndef OS_WIN
TEST_P(EnvPosixTestWithParam, RunMany) {
  std::atomic&lt;int&gt; last_id(0);

  struct CB {
    std::atomic&lt;int&gt;* last_id_ptr;  // Pointer to shared slot
    int id;                         // Order# for the execution of this callback

    CB(std::atomic&lt;int&gt;* p, int i) : last_id_ptr(p), id(i) {}

    static void Run(void* v) {
      CB* cb = reinterpret_cast&lt;CB*&gt;(v);
      int cur = cb-&gt;last_id_ptr-&gt;load();
      ASSERT_EQ(cb-&gt;id - 1, cur);
      cb-&gt;last_id_ptr-&gt;store(cb-&gt;id);
    }
  };

  // Schedule in different order than start time
  CB cb1(&amp;last_id, 1);
  CB cb2(&amp;last_id, 2);
  CB cb3(&amp;last_id, 3);
  CB cb4(&amp;last_id, 4);
  env_-&gt;Schedule(&amp;CB::Run, &amp;cb1);
  env_-&gt;Schedule(&amp;CB::Run, &amp;cb2);
  env_-&gt;Schedule(&amp;CB::Run, &amp;cb3);
  env_-&gt;Schedule(&amp;CB::Run, &amp;cb4);

  Env::Default()-&gt;SleepForMicroseconds(kDelayMicros);
  int cur = last_id.load(std::memory_order_acquire);
  ASSERT_EQ(4, cur);
  WaitThreadPoolsEmpty();
}
#endif

struct State {
  port::Mutex mu;
  int val;
  int num_running;
};

static void ThreadBody(void* arg) {
  State* s = reinterpret_cast&lt;State*&gt;(arg);
  s-&gt;mu.Lock();
  s-&gt;val += 1;
  s-&gt;num_running -= 1;
  s-&gt;mu.Unlock();
}

TEST_P(EnvPosixTestWithParam, StartThread) {
  State state;
  state.val = 0;
  state.num_running = 3;
  for (int i = 0; i &lt; 3; i++) {
    env_-&gt;StartThread(&amp;ThreadBody, &amp;state);
  }
  while (true) {
    state.mu.Lock();
    int num = state.num_running;
    state.mu.Unlock();
    if (num == 0) {
      break;
    }
    Env::Default()-&gt;SleepForMicroseconds(kDelayMicros);
  }
  ASSERT_EQ(state.val, 3);
  WaitThreadPoolsEmpty();
}

TEST_P(EnvPosixTestWithParam, TwoPools) {
  // Data structures to signal tasks to run.
  port::Mutex mutex;
  port::CondVar cv(&amp;mutex);
  bool should_start = false;

  class CB {
   public:
    CB(const std::string&amp; pool_name, int pool_size, port::Mutex* trigger_mu,
       port::CondVar* trigger_cv, bool* _should_start)
        : mu_(),
          num_running_(0),
          num_finished_(0),
          pool_size_(pool_size),
          pool_name_(pool_name),
          trigger_mu_(trigger_mu),
          trigger_cv_(trigger_cv),
          should_start_(_should_start) {}

    static void Run(void* v) {
      CB* cb = reinterpret_cast&lt;CB*&gt;(v);
      cb-&gt;Run();
    }

    void Run() {
      {
        MutexLock l(&amp;mu_);
        num_running_++;
        // make sure we don&#039;t have more than pool_size_ jobs running.
        ASSERT_LE(num_running_, pool_size_.load());
      }

      {
        MutexLock l(trigger_mu_);
        while (!(*should_start_)) {
          trigger_cv_-&gt;Wait();
        }
      }

      {
        MutexLock l(&amp;mu_);
        num_running_--;
        num_finished_++;
      }
    }

    int NumFinished() {
      MutexLock l(&amp;mu_);
      return num_finished_;
    }

    void Reset(int pool_size) {
      pool_size_.store(pool_size);
      num_finished_ = 0;
    }

   private:
    port::Mutex mu_;
    int num_running_;
    int num_finished_;
    std::atomic&lt;int&gt; pool_size_;
    std::string pool_name_;
    port::Mutex* trigger_mu_;
    port::CondVar* trigger_cv_;
    bool* should_start_;
  };

  const int kLowPoolSize = 2;
  const int kHighPoolSize = 4;
  const int kJobs = 8;

  CB low_pool_job(&quot;low&quot;, kLowPoolSize, &amp;mutex, &amp;cv, &amp;should_start);
  CB high_pool_job(&quot;high&quot;, kHighPoolSize, &amp;mutex, &amp;cv, &amp;should_start);

  env_-&gt;SetBackgroundThreads(kLowPoolSize);
  env_-&gt;SetBackgroundThreads(kHighPoolSize, Env::Priority::HIGH);

  ASSERT_EQ(0U, env_-&gt;GetThreadPoolQueueLen(Env::Priority::LOW));
  ASSERT_EQ(0U, env_-&gt;GetThreadPoolQueueLen(Env::Priority::HIGH));

  // schedule same number of jobs in each pool
  for (int i = 0; i &lt; kJobs; i++) {
    env_-&gt;Schedule(&amp;CB::Run, &amp;low_pool_job);
    env_-&gt;Schedule(&amp;CB::Run, &amp;high_pool_job, Env::Priority::HIGH);
  }
  // Wait a short while for the jobs to be dispatched.
  int sleep_count = 0;
  while ((unsigned int)(kJobs - kLowPoolSize) !=
             env_-&gt;GetThreadPoolQueueLen(Env::Priority::LOW) ||
         (unsigned int)(kJobs - kHighPoolSize) !=
             env_-&gt;GetThreadPoolQueueLen(Env::Priority::HIGH)) {
    env_-&gt;SleepForMicroseconds(kDelayMicros);
    if (++sleep_count &gt; 100) {
      break;
    }
  }

  ASSERT_EQ((unsigned int)(kJobs - kLowPoolSize),
            env_-&gt;GetThreadPoolQueueLen());
  ASSERT_EQ((unsigned int)(kJobs - kLowPoolSize),
            env_-&gt;GetThreadPoolQueueLen(Env::Priority::LOW));
  ASSERT_EQ((unsigned int)(kJobs - kHighPoolSize),
            env_-&gt;GetThreadPoolQueueLen(Env::Priority::HIGH));

  // Trigger jobs to run.
  {
    MutexLock l(&amp;mutex);
    should_start = true;
    cv.SignalAll();
  }

  // wait for all jobs to finish
  while (low_pool_job.NumFinished() &lt; kJobs ||
         high_pool_job.NumFinished() &lt; kJobs) {
    env_-&gt;SleepForMicroseconds(kDelayMicros);
  }

  ASSERT_EQ(0U, env_-&gt;GetThreadPoolQueueLen(Env::Priority::LOW));
  ASSERT_EQ(0U, env_-&gt;GetThreadPoolQueueLen(Env::Priority::HIGH));

  // Hold jobs to schedule;
  should_start = false;

  // call IncBackgroundThreadsIfNeeded to two pools. One increasing and
  // the other decreasing
  env_-&gt;IncBackgroundThreadsIfNeeded(kLowPoolSize - 1, Env::Priority::LOW);
  env_-&gt;IncBackgroundThreadsIfNeeded(kHighPoolSize + 1, Env::Priority::HIGH);
  high_pool_job.Reset(kHighPoolSize + 1);
  low_pool_job.Reset(kLowPoolSize);

  // schedule same number of jobs in each pool
  for (int i = 0; i &lt; kJobs; i++) {
    env_-&gt;Schedule(&amp;CB::Run, &amp;low_pool_job);
    env_-&gt;Schedule(&amp;CB::Run, &amp;high_pool_job, Env::Priority::HIGH);
  }
  // Wait a short while for the jobs to be dispatched.
  sleep_count = 0;
  while ((unsigned int)(kJobs - kLowPoolSize) !=
             env_-&gt;GetThreadPoolQueueLen(Env::Priority::LOW) ||
         (unsigned int)(kJobs - (kHighPoolSize + 1)) !=
             env_-&gt;GetThreadPoolQueueLen(Env::Priority::HIGH)) {
    env_-&gt;SleepForMicroseconds(kDelayMicros);
    if (++sleep_count &gt; 100) {
      break;
    }
  }
  ASSERT_EQ((unsigned int)(kJobs - kLowPoolSize),
            env_-&gt;GetThreadPoolQueueLen());
  ASSERT_EQ((unsigned int)(kJobs - kLowPoolSize),
            env_-&gt;GetThreadPoolQueueLen(Env::Priority::LOW));
  ASSERT_EQ((unsigned int)(kJobs - (kHighPoolSize + 1)),
            env_-&gt;GetThreadPoolQueueLen(Env::Priority::HIGH));

  // Trigger jobs to run.
  {
    MutexLock l(&amp;mutex);
    should_start = true;
    cv.SignalAll();
  }

  // wait for all jobs to finish
  while (low_pool_job.NumFinished() &lt; kJobs ||
         high_pool_job.NumFinished() &lt; kJobs) {
    env_-&gt;SleepForMicroseconds(kDelayMicros);
  }

  env_-&gt;SetBackgroundThreads(kHighPoolSize, Env::Priority::HIGH);
  WaitThreadPoolsEmpty();
}

TEST_P(EnvPosixTestWithParam, DecreaseNumBgThreads) {
  constexpr int kWaitMicros = 60000000; // 1min

  std::vector&lt;test::SleepingBackgroundTask&gt; tasks(10);

  // Set number of thread to 1 first.
  env_-&gt;SetBackgroundThreads(1, Env::Priority::HIGH);

  // Schedule 3 tasks. 0 running; Task 1, 2 waiting.
  for (size_t i = 0; i &lt; 3; i++) {
    env_-&gt;Schedule(&amp;test::SleepingBackgroundTask::DoSleepTask, &amp;tasks[i],
                   Env::Priority::HIGH);
  }
  ASSERT_FALSE(tasks[0].TimedWaitUntilSleeping(kWaitMicros));
  ASSERT_EQ(2U, env_-&gt;GetThreadPoolQueueLen(Env::Priority::HIGH));
  ASSERT_TRUE(tasks[0].IsSleeping());
  ASSERT_TRUE(!tasks[1].IsSleeping());
  ASSERT_TRUE(!tasks[2].IsSleeping());

  // Increase to 2 threads. Task 0, 1 running; 2 waiting
  env_-&gt;SetBackgroundThreads(2, Env::Priority::HIGH);
  ASSERT_FALSE(tasks[1].TimedWaitUntilSleeping(kWaitMicros));
  ASSERT_EQ(1U, env_-&gt;GetThreadPoolQueueLen(Env::Priority::HIGH));
  ASSERT_TRUE(tasks[0].IsSleeping());
  ASSERT_TRUE(tasks[1].IsSleeping());
  ASSERT_TRUE(!tasks[2].IsSleeping());

  // Shrink back to 1 thread. Still task 0, 1 running, 2 waiting
  env_-&gt;SetBackgroundThreads(1, Env::Priority::HIGH);
  Env::Default()-&gt;SleepForMicroseconds(kDelayMicros);
  ASSERT_EQ(1U, env_-&gt;GetThreadPoolQueueLen(Env::Priority::HIGH));
  ASSERT_TRUE(tasks[0].IsSleeping());
  ASSERT_TRUE(tasks[1].IsSleeping());
  ASSERT_TRUE(!tasks[2].IsSleeping());

  // The last task finishes. Task 0 running, 2 waiting.
  tasks[1].WakeUp();
  ASSERT_FALSE(tasks[1].TimedWaitUntilDone(kWaitMicros));
  ASSERT_EQ(1U, env_-&gt;GetThreadPoolQueueLen(Env::Priority::HIGH));
  ASSERT_TRUE(tasks[0].IsSleeping());
  ASSERT_TRUE(!tasks[1].IsSleeping());
  ASSERT_TRUE(!tasks[2].IsSleeping());

  // Increase to 5 threads. Task 0 and 2 running.
  env_-&gt;SetBackgroundThreads(5, Env::Priority::HIGH);
  ASSERT_FALSE(tasks[2].TimedWaitUntilSleeping(kWaitMicros));
  ASSERT_EQ(0U, env_-&gt;GetThreadPoolQueueLen(Env::Priority::HIGH));
  ASSERT_TRUE(tasks[0].IsSleeping());
  ASSERT_TRUE(!tasks[1].IsSleeping());
  ASSERT_TRUE(tasks[2].IsSleeping());

  // Change number of threads a couple of times while there is no sufficient
  // tasks.
  env_-&gt;SetBackgroundThreads(7, Env::Priority::HIGH);
  tasks[2].WakeUp();
  ASSERT_FALSE(tasks[2].TimedWaitUntilDone(kWaitMicros));
  ASSERT_EQ(0U, env_-&gt;GetThreadPoolQueueLen(Env::Priority::HIGH));
  env_-&gt;SetBackgroundThreads(3, Env::Priority::HIGH);
  Env::Default()-&gt;SleepForMicroseconds(kDelayMicros);
  ASSERT_EQ(0U, env_-&gt;GetThreadPoolQueueLen(Env::Priority::HIGH));
  env_-&gt;SetBackgroundThreads(4, Env::Priority::HIGH);
  Env::Default()-&gt;SleepForMicroseconds(kDelayMicros);
  ASSERT_EQ(0U, env_-&gt;GetThreadPoolQueueLen(Env::Priority::HIGH));
  env_-&gt;SetBackgroundThreads(5, Env::Priority::HIGH);
  Env::Default()-&gt;SleepForMicroseconds(kDelayMicros);
  ASSERT_EQ(0U, env_-&gt;GetThreadPoolQueueLen(Env::Priority::HIGH));
  env_-&gt;SetBackgroundThreads(4, Env::Priority::HIGH);
  Env::Default()-&gt;SleepForMicroseconds(kDelayMicros);
  ASSERT_EQ(0U, env_-&gt;GetThreadPoolQueueLen(Env::Priority::HIGH));

  Env::Default()-&gt;SleepForMicroseconds(kDelayMicros * 50);

  // Enqueue 5 more tasks. Thread pool size now is 4.
  // Task 0, 3, 4, 5 running;6, 7 waiting.
  for (size_t i = 3; i &lt; 8; i++) {
    env_-&gt;Schedule(&amp;test::SleepingBackgroundTask::DoSleepTask, &amp;tasks[i],
                   Env::Priority::HIGH);
  }
  for (size_t i = 3; i &lt;= 5; i++) {
    ASSERT_FALSE(tasks[i].TimedWaitUntilSleeping(kWaitMicros));
  }
  ASSERT_EQ(2U, env_-&gt;GetThreadPoolQueueLen(Env::Priority::HIGH));
  ASSERT_TRUE(tasks[0].IsSleeping());
  ASSERT_TRUE(!tasks[1].IsSleeping());
  ASSERT_TRUE(!tasks[2].IsSleeping());
  ASSERT_TRUE(tasks[3].IsSleeping());
  ASSERT_TRUE(tasks[4].IsSleeping());
  ASSERT_TRUE(tasks[5].IsSleeping());
  ASSERT_TRUE(!tasks[6].IsSleeping());
  ASSERT_TRUE(!tasks[7].IsSleeping());

  // Wake up task 0, 3 and 4. Task 5, 6, 7 running.
  tasks[0].WakeUp();
  tasks[3].WakeUp();
  tasks[4].WakeUp();

  for (size_t i = 5; i &lt; 8; i++) {
    ASSERT_FALSE(tasks[i].TimedWaitUntilSleeping(kWaitMicros));
  }
  ASSERT_EQ(0U, env_-&gt;GetThreadPoolQueueLen(Env::Priority::HIGH));
  for (size_t i = 5; i &lt; 8; i++) {
    ASSERT_TRUE(tasks[i].IsSleeping());
  }

  // Shrink back to 1 thread. Still task 5, 6, 7 running
  env_-&gt;SetBackgroundThreads(1, Env::Priority::HIGH);
  Env::Default()-&gt;SleepForMicroseconds(kDelayMicros);
  ASSERT_TRUE(tasks[5].IsSleeping());
  ASSERT_TRUE(tasks[6].IsSleeping());
  ASSERT_TRUE(tasks[7].IsSleeping());

  // Wake up task  6. Task 5, 7 running
  tasks[6].WakeUp();
  ASSERT_FALSE(tasks[6].TimedWaitUntilDone(kWaitMicros));
  ASSERT_TRUE(tasks[5].IsSleeping());
  ASSERT_TRUE(!tasks[6].IsSleeping());
  ASSERT_TRUE(tasks[7].IsSleeping());

  // Wake up threads 7. Task 5 running
  tasks[7].WakeUp();
  ASSERT_FALSE(tasks[7].TimedWaitUntilDone(kWaitMicros));
  ASSERT_TRUE(!tasks[7].IsSleeping());

  // Enqueue thread 8 and 9. Task 5 running; one of 8, 9 might be running.
  env_-&gt;Schedule(&amp;test::SleepingBackgroundTask::DoSleepTask, &amp;tasks[8],
                 Env::Priority::HIGH);
  env_-&gt;Schedule(&amp;test::SleepingBackgroundTask::DoSleepTask, &amp;tasks[9],
                 Env::Priority::HIGH);
  Env::Default()-&gt;SleepForMicroseconds(kDelayMicros);
  ASSERT_GT(env_-&gt;GetThreadPoolQueueLen(Env::Priority::HIGH), (unsigned int)0);
  ASSERT_TRUE(!tasks[8].IsSleeping() || !tasks[9].IsSleeping());

  // Increase to 4 threads. Task 5, 8, 9 running.
  env_-&gt;SetBackgroundThreads(4, Env::Priority::HIGH);
  Env::Default()-&gt;SleepForMicroseconds(kDelayMicros);
  ASSERT_EQ((unsigned int)0, env_-&gt;GetThreadPoolQueueLen(Env::Priority::HIGH));
  ASSERT_TRUE(tasks[8].IsSleeping());
  ASSERT_TRUE(tasks[9].IsSleeping());

  // Shrink to 1 thread
  env_-&gt;SetBackgroundThreads(1, Env::Priority::HIGH);

  // Wake up thread 9.
  tasks[9].WakeUp();
  ASSERT_FALSE(tasks[9].TimedWaitUntilDone(kWaitMicros));
  ASSERT_TRUE(!tasks[9].IsSleeping());
  ASSERT_TRUE(tasks[8].IsSleeping());

  // Wake up thread 8
  tasks[8].WakeUp();
  ASSERT_FALSE(tasks[8].TimedWaitUntilDone(kWaitMicros));
  ASSERT_TRUE(!tasks[8].IsSleeping());

  // Wake up the last thread
  tasks[5].WakeUp();
  ASSERT_FALSE(tasks[5].TimedWaitUntilDone(kWaitMicros));
  WaitThreadPoolsEmpty();
}

#if (defined OS_LINUX || defined OS_WIN)
// Travis doesn&#039;t support fallocate or getting unique ID from files for whatever
// reason.
#ifndef TRAVIS

namespace {
bool IsSingleVarint(const std::string&amp; s) {
  Slice slice(s);

  uint64_t v;
  if (!GetVarint64(&amp;slice, &amp;v)) {
    return false;
  }

  return slice.size() == 0;
}

bool IsUniqueIDValid(const std::string&amp; s) {
  return !s.empty() &amp;&amp; !IsSingleVarint(s);
}

const size_t MAX_ID_SIZE = 100;
char temp_id[MAX_ID_SIZE];


}  // namespace

// Determine whether we can use the FS_IOC_GETVERSION ioctl
// on a file in directory DIR.  Create a temporary file therein,
// try to apply the ioctl (save that result), cleanup and
// return the result.  Return true if it is supported, and
// false if anything fails.
// Note that this function &quot;knows&quot; that dir has just been created
// and is empty, so we create a simply-named test file: &quot;f&quot;.
bool ioctl_support__FS_IOC_GETVERSION(const std::string&amp; dir) {
#ifdef OS_WIN
  return true;
#else
  const std::string file = dir + &quot;/f&quot;;
  int fd;
  do {
    fd = open(file.c_str(), O_CREAT | O_RDWR | O_TRUNC, 0644);
  } while (fd &lt; 0 &amp;&amp; errno == EINTR);
  long int version;
  bool ok = (fd &gt;= 0 &amp;&amp; ioctl(fd, FS_IOC_GETVERSION, &amp;version) &gt;= 0);

  close(fd);
  unlink(file.c_str());

  return ok;
#endif
}

// To ensure that Env::GetUniqueId-related tests work correctly, the files
// should be stored in regular storage like &quot;hard disk&quot; or &quot;flash device&quot;,
// and not on a tmpfs file system (like /dev/shm and /tmp on some systems).
// Otherwise we cannot get the correct id.
//
// This function serves as the replacement for test::TmpDir(), which may be
// customized to be on a file system that doesn&#039;t work with GetUniqueId().

class IoctlFriendlyTmpdir {
 public:
  explicit IoctlFriendlyTmpdir() {
    char dir_buf[100];

    const char *fmt = &quot;%s/rocksdb.XXXXXX&quot;;
    const char *tmp = getenv(&quot;TEST_IOCTL_FRIENDLY_TMPDIR&quot;);

#ifdef OS_WIN
#define rmdir _rmdir
    if(tmp == nullptr) {
      tmp = getenv(&quot;TMP&quot;);
    }

    snprintf(dir_buf, sizeof dir_buf, fmt, tmp);
    auto result = _mktemp(dir_buf);
    assert(result != nullptr);
    BOOL ret = CreateDirectory(dir_buf, NULL);
    assert(ret == TRUE);
    dir_ = dir_buf;
#else
    std::list&lt;std::string&gt; candidate_dir_list = {&quot;/var/tmp&quot;, &quot;/tmp&quot;};

    // If $TEST_IOCTL_FRIENDLY_TMPDIR/rocksdb.XXXXXX fits, use
    // $TEST_IOCTL_FRIENDLY_TMPDIR; subtract 2 for the &quot;%s&quot;, and
    // add 1 for the trailing NUL byte.
    if (tmp &amp;&amp; strlen(tmp) + strlen(fmt) - 2 + 1 &lt;= sizeof dir_buf) {
      // use $TEST_IOCTL_FRIENDLY_TMPDIR value
      candidate_dir_list.push_front(tmp);
    }

    for (const std::string&amp; d : candidate_dir_list) {
      snprintf(dir_buf, sizeof dir_buf, fmt, d.c_str());
      if (mkdtemp(dir_buf)) {
        if (ioctl_support__FS_IOC_GETVERSION(dir_buf)) {
          dir_ = dir_buf;
          return;
        } else {
          // Diagnose ioctl-related failure only if this is the
          // directory specified via that envvar.
          if (tmp &amp;&amp; tmp == d) {
            fprintf(stderr, &quot;TEST_IOCTL_FRIENDLY_TMPDIR-specified directory is &quot;
                    &quot;not suitable: %s\n&quot;, d.c_str());
          }
          rmdir(dir_buf);  // ignore failure
        }
      } else {
        // mkdtemp failed: diagnose it, but don&#039;t give up.
        fprintf(stderr, &quot;mkdtemp(%s/...) failed: %s\n&quot;, d.c_str(),
                strerror(errno));
      }
    }

    fprintf(stderr, &quot;failed to find an ioctl-friendly temporary directory;&quot;
            &quot; specify one via the TEST_IOCTL_FRIENDLY_TMPDIR envvar\n&quot;);
    std::abort();
#endif
}

  ~IoctlFriendlyTmpdir() {
    rmdir(dir_.c_str());
  }

  const std::string&amp; name() const {
    return dir_;
  }

 private:
  std::string dir_;
};

#ifndef ROCKSDB_LITE
TEST_F(EnvPosixTest, PositionedAppend) {
  std::unique_ptr&lt;WritableFile&gt; writable_file;
  EnvOptions options;
  options.use_direct_writes = true;
  options.use_mmap_writes = false;
  IoctlFriendlyTmpdir ift;
  ASSERT_OK(env_-&gt;NewWritableFile(ift.name() + &quot;/f&quot;, &amp;writable_file, options));
  const size_t kBlockSize = 4096;
  const size_t kDataSize = kPageSize;
  // Write a page worth of &#039;a&#039;
  auto data_ptr = NewAligned(kDataSize, &#039;a&#039;);
  Slice data_a(data_ptr.get(), kDataSize);
  ASSERT_OK(writable_file-&gt;PositionedAppend(data_a, 0U));
  // Write a page worth of &#039;b&#039; right after the first sector
  data_ptr = NewAligned(kDataSize, &#039;b&#039;);
  Slice data_b(data_ptr.get(), kDataSize);
  ASSERT_OK(writable_file-&gt;PositionedAppend(data_b, kBlockSize));
  ASSERT_OK(writable_file-&gt;Close());
  // The file now has 1 sector worth of a followed by a page worth of b

  // Verify the above
  std::unique_ptr&lt;SequentialFile&gt; seq_file;
  ASSERT_OK(env_-&gt;NewSequentialFile(ift.name() + &quot;/f&quot;, &amp;seq_file, options));
  size_t scratch_len = kPageSize * 2;
  std::unique_ptr&lt;char[]&gt; scratch(new char[scratch_len]);
  Slice result;
  ASSERT_OK(seq_file-&gt;Read(scratch_len, &amp;result, scratch.get()));
  ASSERT_EQ(kPageSize + kBlockSize, result.size());
  ASSERT_EQ(&#039;a&#039;, result[kBlockSize - 1]);
  ASSERT_EQ(&#039;b&#039;, result[kBlockSize]);
}
#endif  // !ROCKSDB_LITE

// `GetUniqueId()` temporarily returns zero on Windows. `BlockBasedTable` can
// handle a return value of zero but this test case cannot.
#ifndef OS_WIN
TEST_P(EnvPosixTestWithParam, RandomAccessUniqueID) {
  // Create file.
  if (env_ == Env::Default()) {
    EnvOptions soptions;
    soptions.use_direct_reads = soptions.use_direct_writes = direct_io_;
    IoctlFriendlyTmpdir ift;
    std::string fname = ift.name() + &quot;/testfile&quot;;
    std::unique_ptr&lt;WritableFile&gt; wfile;
    ASSERT_OK(env_-&gt;NewWritableFile(fname, &amp;wfile, soptions));

    std::unique_ptr&lt;RandomAccessFile&gt; file;

    // Get Unique ID
    ASSERT_OK(env_-&gt;NewRandomAccessFile(fname, &amp;file, soptions));
    size_t id_size = file-&gt;GetUniqueId(temp_id, MAX_ID_SIZE);
    ASSERT_TRUE(id_size &gt; 0);
    std::string unique_id1(temp_id, id_size);
    ASSERT_TRUE(IsUniqueIDValid(unique_id1));

    // Get Unique ID again
    ASSERT_OK(env_-&gt;NewRandomAccessFile(fname, &amp;file, soptions));
    id_size = file-&gt;GetUniqueId(temp_id, MAX_ID_SIZE);
    ASSERT_TRUE(id_size &gt; 0);
    std::string unique_id2(temp_id, id_size);
    ASSERT_TRUE(IsUniqueIDValid(unique_id2));

    // Get Unique ID again after waiting some time.
    env_-&gt;SleepForMicroseconds(1000000);
    ASSERT_OK(env_-&gt;NewRandomAccessFile(fname, &amp;file, soptions));
    id_size = file-&gt;GetUniqueId(temp_id, MAX_ID_SIZE);
    ASSERT_TRUE(id_size &gt; 0);
    std::string unique_id3(temp_id, id_size);
    ASSERT_TRUE(IsUniqueIDValid(unique_id3));

    // Check IDs are the same.
    ASSERT_EQ(unique_id1, unique_id2);
    ASSERT_EQ(unique_id2, unique_id3);

    // Delete the file
    env_-&gt;DeleteFile(fname);
  }
}
#endif  // !defined(OS_WIN)

// only works in linux platforms
#ifdef ROCKSDB_FALLOCATE_PRESENT
TEST_P(EnvPosixTestWithParam, AllocateTest) {
  if (env_ == Env::Default()) {
    IoctlFriendlyTmpdir ift;
    std::string fname = ift.name() + &quot;/preallocate_testfile&quot;;

    // Try fallocate in a file to see whether the target file system supports
    // it.
    // Skip the test if fallocate is not supported.
    std::string fname_test_fallocate = ift.name() + &quot;/preallocate_testfile_2&quot;;
    int fd = -1;
    do {
      fd = open(fname_test_fallocate.c_str(), O_CREAT | O_RDWR | O_TRUNC, 0644);
    } while (fd &lt; 0 &amp;&amp; errno == EINTR);
    ASSERT_GT(fd, 0);

    int alloc_status = fallocate(fd, 0, 0, 1);

    int err_number = 0;
    if (alloc_status != 0) {
      err_number = errno;
      fprintf(stderr, &quot;Warning: fallocate() fails, %s\n&quot;, strerror(err_number));
    }
    close(fd);
    ASSERT_OK(env_-&gt;DeleteFile(fname_test_fallocate));
    if (alloc_status != 0 &amp;&amp; err_number == EOPNOTSUPP) {
      // The filesystem containing the file does not support fallocate
      return;
    }

    EnvOptions soptions;
    soptions.use_mmap_writes = false;
    soptions.use_direct_reads = soptions.use_direct_writes = direct_io_;
    std::unique_ptr&lt;WritableFile&gt; wfile;
    ASSERT_OK(env_-&gt;NewWritableFile(fname, &amp;wfile, soptions));

    // allocate 100 MB
    size_t kPreallocateSize = 100 * 1024 * 1024;
    size_t kBlockSize = 512;
    size_t kDataSize = 1024 * 1024;
    auto data_ptr = NewAligned(kDataSize, &#039;A&#039;);
    Slice data(data_ptr.get(), kDataSize);
    wfile-&gt;SetPreallocationBlockSize(kPreallocateSize);
    wfile-&gt;PrepareWrite(wfile-&gt;GetFileSize(), kDataSize);
    ASSERT_OK(wfile-&gt;Append(data));
    ASSERT_OK(wfile-&gt;Flush());

    struct stat f_stat;
    ASSERT_EQ(stat(fname.c_str(), &amp;f_stat), 0);
    ASSERT_EQ((unsigned int)kDataSize, f_stat.st_size);
    // verify that blocks are preallocated
    // Note here that we don&#039;t check the exact number of blocks preallocated --
    // we only require that number of allocated blocks is at least what we
    // expect.
    // It looks like some FS give us more blocks that we asked for. That&#039;s fine.
    // It might be worth investigating further.
    ASSERT_LE((unsigned int)(kPreallocateSize / kBlockSize), f_stat.st_blocks);

    // close the file, should deallocate the blocks
    wfile.reset();

    stat(fname.c_str(), &amp;f_stat);
    ASSERT_EQ((unsigned int)kDataSize, f_stat.st_size);
    // verify that preallocated blocks were deallocated on file close
    // Because the FS might give us more blocks, we add a full page to the size
    // and expect the number of blocks to be less or equal to that.
    ASSERT_GE((f_stat.st_size + kPageSize + kBlockSize - 1) / kBlockSize,
              (unsigned int)f_stat.st_blocks);
  }
}
#endif  // ROCKSDB_FALLOCATE_PRESENT

// Returns true if any of the strings in ss are the prefix of another string.
bool HasPrefix(const std::unordered_set&lt;std::string&gt;&amp; ss) {
  for (const std::string&amp; s: ss) {
    if (s.empty()) {
      return true;
    }
    for (size_t i = 1; i &lt; s.size(); ++i) {
      if (ss.count(s.substr(0, i)) != 0) {
        return true;
      }
    }
  }
  return false;
}

// `GetUniqueId()` temporarily returns zero on Windows. `BlockBasedTable` can
// handle a return value of zero but this test case cannot.
#ifndef OS_WIN
TEST_P(EnvPosixTestWithParam, RandomAccessUniqueIDConcurrent) {
  if (env_ == Env::Default()) {
    // Check whether a bunch of concurrently existing files have unique IDs.
    EnvOptions soptions;
    soptions.use_direct_reads = soptions.use_direct_writes = direct_io_;

    // Create the files
    IoctlFriendlyTmpdir ift;
    std::vector&lt;std::string&gt; fnames;
    for (int i = 0; i &lt; 1000; ++i) {
      fnames.push_back(ift.name() + &quot;/&quot; + &quot;testfile&quot; + ToString(i));

      // Create file.
      std::unique_ptr&lt;WritableFile&gt; wfile;
      ASSERT_OK(env_-&gt;NewWritableFile(fnames[i], &amp;wfile, soptions));
    }

    // Collect and check whether the IDs are unique.
    std::unordered_set&lt;std::string&gt; ids;
    for (const std::string fname : fnames) {
      std::unique_ptr&lt;RandomAccessFile&gt; file;
      std::string unique_id;
      ASSERT_OK(env_-&gt;NewRandomAccessFile(fname, &amp;file, soptions));
      size_t id_size = file-&gt;GetUniqueId(temp_id, MAX_ID_SIZE);
      ASSERT_TRUE(id_size &gt; 0);
      unique_id = std::string(temp_id, id_size);
      ASSERT_TRUE(IsUniqueIDValid(unique_id));

      ASSERT_TRUE(ids.count(unique_id) == 0);
      ids.insert(unique_id);
    }

    // Delete the files
    for (const std::string fname : fnames) {
      ASSERT_OK(env_-&gt;DeleteFile(fname));
    }

    ASSERT_TRUE(!HasPrefix(ids));
  }
}

TEST_P(EnvPosixTestWithParam, RandomAccessUniqueIDDeletes) {
  if (env_ == Env::Default()) {
    EnvOptions soptions;
    soptions.use_direct_reads = soptions.use_direct_writes = direct_io_;

    IoctlFriendlyTmpdir ift;
    std::string fname = ift.name() + &quot;/&quot; + &quot;testfile&quot;;

    // Check that after file is deleted we don&#039;t get same ID again in a new
    // file.
    std::unordered_set&lt;std::string&gt; ids;
    for (int i = 0; i &lt; 1000; ++i) {
      // Create file.
      {
        std::unique_ptr&lt;WritableFile&gt; wfile;
        ASSERT_OK(env_-&gt;NewWritableFile(fname, &amp;wfile, soptions));
      }

      // Get Unique ID
      std::string unique_id;
      {
        std::unique_ptr&lt;RandomAccessFile&gt; file;
        ASSERT_OK(env_-&gt;NewRandomAccessFile(fname, &amp;file, soptions));
        size_t id_size = file-&gt;GetUniqueId(temp_id, MAX_ID_SIZE);
        ASSERT_TRUE(id_size &gt; 0);
        unique_id = std::string(temp_id, id_size);
      }

      ASSERT_TRUE(IsUniqueIDValid(unique_id));
      ASSERT_TRUE(ids.count(unique_id) == 0);
      ids.insert(unique_id);

      // Delete the file
      ASSERT_OK(env_-&gt;DeleteFile(fname));
    }

    ASSERT_TRUE(!HasPrefix(ids));
  }
}
#endif  // !defined(OS_WIN)

TEST_P(EnvPosixTestWithParam, MultiRead) {
  EnvOptions soptions;
  soptions.use_direct_reads = soptions.use_direct_writes = direct_io_;
  std::string fname = test::PerThreadDBPath(env_, &quot;testfile&quot;);

  const size_t kSectorSize = 4096;
  const size_t kNumSectors = 8;

  // Create file.
  {
    std::unique_ptr&lt;WritableFile&gt; wfile;
#if !defined(OS_MACOSX) &amp;&amp; !defined(OS_WIN) &amp;&amp; !defined(OS_SOLARIS) &amp;&amp; \
    !defined(OS_AIX)
    if (soptions.use_direct_writes) {
      soptions.use_direct_writes = false;
    }
#endif
    ASSERT_OK(env_-&gt;NewWritableFile(fname, &amp;wfile, soptions));
    for (size_t i = 0; i &lt; kNumSectors; ++i) {
      auto data = NewAligned(kSectorSize * 8, static_cast&lt;char&gt;(i + 1));
      Slice slice(data.get(), kSectorSize);
      ASSERT_OK(wfile-&gt;Append(slice));
    }
    ASSERT_OK(wfile-&gt;Close());
  }

  // More attempts to simulate more partial result sequences.
  for (uint32_t attempt = 0; attempt &lt; 20; attempt++) {
    // Random Read
    Random rnd(301 + attempt);
    ROCKSDB_NAMESPACE::SyncPoint::GetInstance()-&gt;SetCallBack(
        &quot;PosixRandomAccessFile::MultiRead:io_uring_result&quot;, [&amp;](void* arg) {
          if (attempt &gt; 0) {
            // No failure in the first attempt.
            size_t&amp; bytes_read = *static_cast&lt;size_t*&gt;(arg);
            if (rnd.OneIn(4)) {
              bytes_read = 0;
            } else if (rnd.OneIn(3)) {
              bytes_read = static_cast&lt;size_t&gt;(
                  rnd.Uniform(static_cast&lt;int&gt;(bytes_read)));
            }
          }
        });
    ROCKSDB_NAMESPACE::SyncPoint::GetInstance()-&gt;EnableProcessing();

    std::unique_ptr&lt;RandomAccessFile&gt; file;
    std::vector&lt;ReadRequest&gt; reqs(3);
    std::vector&lt;std::unique_ptr&lt;char, Deleter&gt;&gt; data;
    uint64_t offset = 0;
    for (size_t i = 0; i &lt; reqs.size(); ++i) {
      reqs[i].offset = offset;
      offset += 2 * kSectorSize;
      reqs[i].len = kSectorSize;
      data.emplace_back(NewAligned(kSectorSize, 0));
      reqs[i].scratch = data.back().get();
    }
#if !defined(OS_MACOSX) &amp;&amp; !defined(OS_WIN) &amp;&amp; !defined(OS_SOLARIS) &amp;&amp; \
    !defined(OS_AIX)
    if (soptions.use_direct_reads) {
      soptions.use_direct_reads = false;
    }
#endif
    ASSERT_OK(env_-&gt;NewRandomAccessFile(fname, &amp;file, soptions));
    ASSERT_OK(file-&gt;MultiRead(reqs.data(), reqs.size()));
    for (size_t i = 0; i &lt; reqs.size(); ++i) {
      auto buf = NewAligned(kSectorSize * 8, static_cast&lt;char&gt;(i * 2 + 1));
      ASSERT_OK(reqs[i].status);
      ASSERT_EQ(memcmp(reqs[i].scratch, buf.get(), kSectorSize), 0);
    }
    ROCKSDB_NAMESPACE::SyncPoint::GetInstance()-&gt;DisableProcessing();
  }
}

// Only works in linux platforms
#ifdef OS_WIN
TEST_P(EnvPosixTestWithParam, DISABLED_InvalidateCache) {
#else
TEST_P(EnvPosixTestWithParam, InvalidateCache) {
#endif
  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()-&gt;EnableProcessing();
  EnvOptions soptions;
  soptions.use_direct_reads = soptions.use_direct_writes = direct_io_;
  std::string fname = test::PerThreadDBPath(env_, &quot;testfile&quot;);

  const size_t kSectorSize = 512;
  auto data = NewAligned(kSectorSize, 0);
  Slice slice(data.get(), kSectorSize);

  // Create file.
  {
    std::unique_ptr&lt;WritableFile&gt; wfile;
#if !defined(OS_MACOSX) &amp;&amp; !defined(OS_WIN) &amp;&amp; !defined(OS_SOLARIS) &amp;&amp; !defined(OS_AIX)
      if (soptions.use_direct_writes) {
        soptions.use_direct_writes = false;
      }
#endif
      ASSERT_OK(env_-&gt;NewWritableFile(fname, &amp;wfile, soptions));
      ASSERT_OK(wfile-&gt;Append(slice));
      ASSERT_OK(wfile-&gt;InvalidateCache(0, 0));
      ASSERT_OK(wfile-&gt;Close());
  }

    // Random Read
    {
      std::unique_ptr&lt;RandomAccessFile&gt; file;
      auto scratch = NewAligned(kSectorSize, 0);
      Slice result;
#if !defined(OS_MACOSX) &amp;&amp; !defined(OS_WIN) &amp;&amp; !defined(OS_SOLARIS) &amp;&amp; !defined(OS_AIX)
      if (soptions.use_direct_reads) {
        soptions.use_direct_reads = false;
      }
#endif
      ASSERT_OK(env_-&gt;NewRandomAccessFile(fname, &amp;file, soptions));
      ASSERT_OK(file-&gt;Read(0, kSectorSize, &amp;result, scratch.get()));
      ASSERT_EQ(memcmp(scratch.get(), data.get(), kSectorSize), 0);
      ASSERT_OK(file-&gt;InvalidateCache(0, 11));
      ASSERT_OK(file-&gt;InvalidateCache(0, 0));
    }

    // Sequential Read
    {
      std::unique_ptr&lt;SequentialFile&gt; file;
      auto scratch = NewAligned(kSectorSize, 0);
      Slice result;
#if !defined(OS_MACOSX) &amp;&amp; !defined(OS_WIN) &amp;&amp; !defined(OS_SOLARIS) &amp;&amp; !defined(OS_AIX)
      if (soptions.use_direct_reads) {
        soptions.use_direct_reads = false;
      }
#endif
      ASSERT_OK(env_-&gt;NewSequentialFile(fname, &amp;file, soptions));
      if (file-&gt;use_direct_io()) {
        ASSERT_OK(file-&gt;PositionedRead(0, kSectorSize, &amp;result, scratch.get()));
      } else {
        ASSERT_OK(file-&gt;Read(kSectorSize, &amp;result, scratch.get()));
      }
      ASSERT_EQ(memcmp(scratch.get(), data.get(), kSectorSize), 0);
      ASSERT_OK(file-&gt;InvalidateCache(0, 11));
      ASSERT_OK(file-&gt;InvalidateCache(0, 0));
    }
    // Delete the file
    ASSERT_OK(env_-&gt;DeleteFile(fname));
    ROCKSDB_NAMESPACE::SyncPoint::GetInstance()-&gt;ClearTrace();
}
#endif  // not TRAVIS
#endif  // OS_LINUX || OS_WIN

class TestLogger : public Logger {
 public:
  using Logger::Logv;
  void Logv(const char* format, va_list ap) override {
    log_count++;

    char new_format[550];
    std::fill_n(new_format, sizeof(new_format), &#039;2&#039;);
    {
      va_list backup_ap;
      va_copy(backup_ap, ap);
      int n = vsnprintf(new_format, sizeof(new_format) - 1, format, backup_ap);
      // 48 bytes for extra information + bytes allocated

// When we have n == -1 there is not a terminating zero expected
#ifdef OS_WIN
      if (n &lt; 0) {
        char_0_count++;
      }
#endif

      if (new_format[0] == &#039;[&#039;) {
        // &quot;[DEBUG] &quot;
        ASSERT_TRUE(n &lt;= 56 + (512 - static_cast&lt;int&gt;(sizeof(struct timeval))));
      } else {
        ASSERT_TRUE(n &lt;= 48 + (512 - static_cast&lt;int&gt;(sizeof(struct timeval))));
      }
      va_end(backup_ap);
    }

    for (size_t i = 0; i &lt; sizeof(new_format); i++) {
      if (new_format[i] == &#039;x&#039;) {
        char_x_count++;
      } else if (new_format[i] == &#039;\0&#039;) {
        char_0_count++;
      }
    }
  }
  int log_count;
  int char_x_count;
  int char_0_count;
};

TEST_P(EnvPosixTestWithParam, LogBufferTest) {
  TestLogger test_logger;
  test_logger.SetInfoLogLevel(InfoLogLevel::INFO_LEVEL);
  test_logger.log_count = 0;
  test_logger.char_x_count = 0;
  test_logger.char_0_count = 0;
  LogBuffer log_buffer(InfoLogLevel::INFO_LEVEL, &amp;test_logger);
  LogBuffer log_buffer_debug(DEBUG_LEVEL, &amp;test_logger);

  char bytes200[200];
  std::fill_n(bytes200, sizeof(bytes200), &#039;1&#039;);
  bytes200[sizeof(bytes200) - 1] = &#039;\0&#039;;
  char bytes600[600];
  std::fill_n(bytes600, sizeof(bytes600), &#039;1&#039;);
  bytes600[sizeof(bytes600) - 1] = &#039;\0&#039;;
  char bytes9000[9000];
  std::fill_n(bytes9000, sizeof(bytes9000), &#039;1&#039;);
  bytes9000[sizeof(bytes9000) - 1] = &#039;\0&#039;;

  ROCKS_LOG_BUFFER(&amp;log_buffer, &quot;x%sx&quot;, bytes200);
  ROCKS_LOG_BUFFER(&amp;log_buffer, &quot;x%sx&quot;, bytes600);
  ROCKS_LOG_BUFFER(&amp;log_buffer, &quot;x%sx%sx%sx&quot;, bytes200, bytes200, bytes200);
  ROCKS_LOG_BUFFER(&amp;log_buffer, &quot;x%sx%sx&quot;, bytes200, bytes600);
  ROCKS_LOG_BUFFER(&amp;log_buffer, &quot;x%sx%sx&quot;, bytes600, bytes9000);

  ROCKS_LOG_BUFFER(&amp;log_buffer_debug, &quot;x%sx&quot;, bytes200);
  test_logger.SetInfoLogLevel(DEBUG_LEVEL);
  ROCKS_LOG_BUFFER(&amp;log_buffer_debug, &quot;x%sx%sx%sx&quot;, bytes600, bytes9000,
                   bytes200);

  ASSERT_EQ(0, test_logger.log_count);
  log_buffer.FlushBufferToLog();
  log_buffer_debug.FlushBufferToLog();
  ASSERT_EQ(6, test_logger.log_count);
  ASSERT_EQ(6, test_logger.char_0_count);
  ASSERT_EQ(10, test_logger.char_x_count);
}

class TestLogger2 : public Logger {
 public:
  explicit TestLogger2(size_t max_log_size) : max_log_size_(max_log_size) {}
  using Logger::Logv;
  void Logv(const char* format, va_list ap) override {
    char new_format[2000];
    std::fill_n(new_format, sizeof(new_format), &#039;2&#039;);
    {
      va_list backup_ap;
      va_copy(backup_ap, ap);
      int n = vsnprintf(new_format, sizeof(new_format) - 1, format, backup_ap);
      // 48 bytes for extra information + bytes allocated
      ASSERT_TRUE(
          n &lt;= 48 + static_cast&lt;int&gt;(max_log_size_ - sizeof(struct timeval)));
      ASSERT_TRUE(n &gt; static_cast&lt;int&gt;(max_log_size_ - sizeof(struct timeval)));
      va_end(backup_ap);
    }
  }
  size_t max_log_size_;
};

TEST_P(EnvPosixTestWithParam, LogBufferMaxSizeTest) {
  char bytes9000[9000];
  std::fill_n(bytes9000, sizeof(bytes9000), &#039;1&#039;);
  bytes9000[sizeof(bytes9000) - 1] = &#039;\0&#039;;

  for (size_t max_log_size = 256; max_log_size &lt;= 1024;
       max_log_size += 1024 - 256) {
    TestLogger2 test_logger(max_log_size);
    test_logger.SetInfoLogLevel(InfoLogLevel::INFO_LEVEL);
    LogBuffer log_buffer(InfoLogLevel::INFO_LEVEL, &amp;test_logger);
    ROCKS_LOG_BUFFER_MAX_SZ(&amp;log_buffer, max_log_size, &quot;%s&quot;, bytes9000);
    log_buffer.FlushBufferToLog();
  }
}

TEST_P(EnvPosixTestWithParam, Preallocation) {
  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()-&gt;EnableProcessing();
  const std::string src = test::PerThreadDBPath(env_, &quot;testfile&quot;);
  std::unique_ptr&lt;WritableFile&gt; srcfile;
  EnvOptions soptions;
  soptions.use_direct_reads = soptions.use_direct_writes = direct_io_;
#if !defined(OS_MACOSX) &amp;&amp; !defined(OS_WIN) &amp;&amp; !defined(OS_SOLARIS) &amp;&amp; !defined(OS_AIX) &amp;&amp; !defined(OS_OPENBSD) &amp;&amp; !defined(OS_FREEBSD)
    if (soptions.use_direct_writes) {
      ROCKSDB_NAMESPACE::SyncPoint::GetInstance()-&gt;SetCallBack(
          &quot;NewWritableFile:O_DIRECT&quot;, [&amp;](void* arg) {
            int* val = static_cast&lt;int*&gt;(arg);
            *val &amp;= ~O_DIRECT;
          });
    }
#endif
    ASSERT_OK(env_-&gt;NewWritableFile(src, &amp;srcfile, soptions));
    srcfile-&gt;SetPreallocationBlockSize(1024 * 1024);

    // No writes should mean no preallocation
    size_t block_size, last_allocated_block;
    srcfile-&gt;GetPreallocationStatus(&amp;block_size, &amp;last_allocated_block);
    ASSERT_EQ(last_allocated_block, 0UL);

    // Small write should preallocate one block
    size_t kStrSize = 4096;
    auto data = NewAligned(kStrSize, &#039;A&#039;);
    Slice str(data.get(), kStrSize);
    srcfile-&gt;PrepareWrite(srcfile-&gt;GetFileSize(), kStrSize);
    srcfile-&gt;Append(str);
    srcfile-&gt;GetPreallocationStatus(&amp;block_size, &amp;last_allocated_block);
    ASSERT_EQ(last_allocated_block, 1UL);

    // Write an entire preallocation block, make sure we increased by two.
    {
      auto buf_ptr = NewAligned(block_size, &#039; &#039;);
      Slice buf(buf_ptr.get(), block_size);
      srcfile-&gt;PrepareWrite(srcfile-&gt;GetFileSize(), block_size);
      srcfile-&gt;Append(buf);
      srcfile-&gt;GetPreallocationStatus(&amp;block_size, &amp;last_allocated_block);
      ASSERT_EQ(last_allocated_block, 2UL);
    }

    // Write five more blocks at once, ensure we&#039;re where we need to be.
    {
      auto buf_ptr = NewAligned(block_size * 5, &#039; &#039;);
      Slice buf = Slice(buf_ptr.get(), block_size * 5);
      srcfile-&gt;PrepareWrite(srcfile-&gt;GetFileSize(), buf.size());
      srcfile-&gt;Append(buf);
      srcfile-&gt;GetPreallocationStatus(&amp;block_size, &amp;last_allocated_block);
      ASSERT_EQ(last_allocated_block, 7UL);
    }
    ROCKSDB_NAMESPACE::SyncPoint::GetInstance()-&gt;ClearTrace();
}

// Test that the two ways to get children file attributes (in bulk or
// individually) behave consistently.
TEST_P(EnvPosixTestWithParam, ConsistentChildrenAttributes) {
  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()-&gt;EnableProcessing();
  EnvOptions soptions;
  soptions.use_direct_reads = soptions.use_direct_writes = direct_io_;
  const int kNumChildren = 10;

  std::string data;
  for (int i = 0; i &lt; kNumChildren; ++i) {
    const std::string path =
        test::TmpDir(env_) + &quot;/&quot; + &quot;testfile_&quot; + std::to_string(i);
    std::unique_ptr&lt;WritableFile&gt; file;
#if !defined(OS_MACOSX) &amp;&amp; !defined(OS_WIN) &amp;&amp; !defined(OS_SOLARIS) &amp;&amp; !defined(OS_AIX) &amp;&amp; !defined(OS_OPENBSD) &amp;&amp; !defined(OS_FREEBSD)
      if (soptions.use_direct_writes) {
        ROCKSDB_NAMESPACE::SyncPoint::GetInstance()-&gt;SetCallBack(
            &quot;NewWritableFile:O_DIRECT&quot;, [&amp;](void* arg) {
              int* val = static_cast&lt;int*&gt;(arg);
              *val &amp;= ~O_DIRECT;
            });
      }
#endif
      ASSERT_OK(env_-&gt;NewWritableFile(path, &amp;file, soptions));
      auto buf_ptr = NewAligned(data.size(), &#039;T&#039;);
      Slice buf(buf_ptr.get(), data.size());
      file-&gt;Append(buf);
      data.append(std::string(4096, &#039;T&#039;));
  }

    std::vector&lt;Env::FileAttributes&gt; file_attrs;
    ASSERT_OK(env_-&gt;GetChildrenFileAttributes(test::TmpDir(env_), &amp;file_attrs));
    for (int i = 0; i &lt; kNumChildren; ++i) {
      const std::string name = &quot;testfile_&quot; + std::to_string(i);
      const std::string path = test::TmpDir(env_) + &quot;/&quot; + name;

      auto file_attrs_iter = std::find_if(
          file_attrs.begin(), file_attrs.end(),
          [&amp;name](const Env::FileAttributes&amp; fm) { return fm.name == name; });
      ASSERT_TRUE(file_attrs_iter != file_attrs.end());
      uint64_t size;
      ASSERT_OK(env_-&gt;GetFileSize(path, &amp;size));
      ASSERT_EQ(size, 4096 * i);
      ASSERT_EQ(size, file_attrs_iter-&gt;size_bytes);
    }
    ROCKSDB_NAMESPACE::SyncPoint::GetInstance()-&gt;ClearTrace();
}

// Test that all WritableFileWrapper forwards all calls to WritableFile.
TEST_P(EnvPosixTestWithParam, WritableFileWrapper) {
  class Base : public WritableFile {
   public:
    mutable int *step_;

    void inc(int x) const {
      EXPECT_EQ(x, (*step_)++);
    }

    explicit Base(int* step) : step_(step) {
      inc(0);
    }

    Status Append(const Slice&amp; /*data*/) override {
      inc(1);
      return Status::OK();
    }

    Status PositionedAppend(const Slice&amp; /*data*/,
                            uint64_t /*offset*/) override {
      inc(2);
      return Status::OK();
    }

    Status Truncate(uint64_t /*size*/) override {
      inc(3);
      return Status::OK();
    }

    Status Close() override {
      inc(4);
      return Status::OK();
    }

    Status Flush() override {
      inc(5);
      return Status::OK();
    }

    Status Sync() override {
      inc(6);
      return Status::OK();
    }

    Status Fsync() override {
      inc(7);
      return Status::OK();
    }

    bool IsSyncThreadSafe() const override {
      inc(8);
      return true;
    }

    bool use_direct_io() const override {
      inc(9);
      return true;
    }

    size_t GetRequiredBufferAlignment() const override {
      inc(10);
      return 0;
    }

    void SetIOPriority(Env::IOPriority /*pri*/) override { inc(11); }

    Env::IOPriority GetIOPriority() override {
      inc(12);
      return Env::IOPriority::IO_LOW;
    }

    void SetWriteLifeTimeHint(Env::WriteLifeTimeHint /*hint*/) override {
      inc(13);
    }

    Env::WriteLifeTimeHint GetWriteLifeTimeHint() override {
      inc(14);
      return Env::WriteLifeTimeHint::WLTH_NOT_SET;
    }

    uint64_t GetFileSize() override {
      inc(15);
      return 0;
    }

    void SetPreallocationBlockSize(size_t /*size*/) override { inc(16); }

    void GetPreallocationStatus(size_t* /*block_size*/,
                                size_t* /*last_allocated_block*/) override {
      inc(17);
    }

    size_t GetUniqueId(char* /*id*/, size_t /*max_size*/) const override {
      inc(18);
      return 0;
    }

    Status InvalidateCache(size_t /*offset*/, size_t /*length*/) override {
      inc(19);
      return Status::OK();
    }

    Status RangeSync(uint64_t /*offset*/, uint64_t /*nbytes*/) override {
      inc(20);
      return Status::OK();
    }

    void PrepareWrite(size_t /*offset*/, size_t /*len*/) override { inc(21); }

    Status Allocate(uint64_t /*offset*/, uint64_t /*len*/) override {
      inc(22);
      return Status::OK();
    }

   public:
    ~Base() override { inc(23); }
  };

  class Wrapper : public WritableFileWrapper {
   public:
    explicit Wrapper(WritableFile* target) : WritableFileWrapper(target) {}
  };

  int step = 0;

  {
    Base b(&amp;step);
    Wrapper w(&amp;b);
    w.Append(Slice());
    w.PositionedAppend(Slice(), 0);
    w.Truncate(0);
    w.Close();
    w.Flush();
    w.Sync();
    w.Fsync();
    w.IsSyncThreadSafe();
    w.use_direct_io();
    w.GetRequiredBufferAlignment();
    w.SetIOPriority(Env::IOPriority::IO_HIGH);
    w.GetIOPriority();
    w.SetWriteLifeTimeHint(Env::WriteLifeTimeHint::WLTH_NOT_SET);
    w.GetWriteLifeTimeHint();
    w.GetFileSize();
    w.SetPreallocationBlockSize(0);
    w.GetPreallocationStatus(nullptr, nullptr);
    w.GetUniqueId(nullptr, 0);
    w.InvalidateCache(0, 0);
    w.RangeSync(0, 0);
    w.PrepareWrite(0, 0);
    w.Allocate(0, 0);
  }

  EXPECT_EQ(24, step);
}

TEST_P(EnvPosixTestWithParam, PosixRandomRWFile) {
  const std::string path = test::PerThreadDBPath(env_, &quot;random_rw_file&quot;);

  env_-&gt;DeleteFile(path);

  std::unique_ptr&lt;RandomRWFile&gt; file;

  // Cannot open non-existing file.
  ASSERT_NOK(env_-&gt;NewRandomRWFile(path, &amp;file, EnvOptions()));

  // Create the file using WriteableFile
  {
    std::unique_ptr&lt;WritableFile&gt; wf;
    ASSERT_OK(env_-&gt;NewWritableFile(path, &amp;wf, EnvOptions()));
  }

  ASSERT_OK(env_-&gt;NewRandomRWFile(path, &amp;file, EnvOptions()));

  char buf[10000];
  Slice read_res;

  ASSERT_OK(file-&gt;Write(0, &quot;ABCD&quot;));
  ASSERT_OK(file-&gt;Read(0, 10, &amp;read_res, buf));
  ASSERT_EQ(read_res.ToString(), &quot;ABCD&quot;);

  ASSERT_OK(file-&gt;Write(2, &quot;XXXX&quot;));
  ASSERT_OK(file-&gt;Read(0, 10, &amp;read_res, buf));
  ASSERT_EQ(read_res.ToString(), &quot;ABXXXX&quot;);

  ASSERT_OK(file-&gt;Write(10, &quot;ZZZ&quot;));
  ASSERT_OK(file-&gt;Read(10, 10, &amp;read_res, buf));
  ASSERT_EQ(read_res.ToString(), &quot;ZZZ&quot;);

  ASSERT_OK(file-&gt;Write(11, &quot;Y&quot;));
  ASSERT_OK(file-&gt;Read(10, 10, &amp;read_res, buf));
  ASSERT_EQ(read_res.ToString(), &quot;ZYZ&quot;);

  ASSERT_OK(file-&gt;Write(200, &quot;FFFFF&quot;));
  ASSERT_OK(file-&gt;Read(200, 10, &amp;read_res, buf));
  ASSERT_EQ(read_res.ToString(), &quot;FFFFF&quot;);

  ASSERT_OK(file-&gt;Write(205, &quot;XXXX&quot;));
  ASSERT_OK(file-&gt;Read(200, 10, &amp;read_res, buf));
  ASSERT_EQ(read_res.ToString(), &quot;FFFFFXXXX&quot;);

  ASSERT_OK(file-&gt;Write(5, &quot;QQQQ&quot;));
  ASSERT_OK(file-&gt;Read(0, 9, &amp;read_res, buf));
  ASSERT_EQ(read_res.ToString(), &quot;ABXXXQQQQ&quot;);

  ASSERT_OK(file-&gt;Read(2, 4, &amp;read_res, buf));
  ASSERT_EQ(read_res.ToString(), &quot;XXXQ&quot;);

  // Close file and reopen it
  file-&gt;Close();
  ASSERT_OK(env_-&gt;NewRandomRWFile(path, &amp;file, EnvOptions()));

  ASSERT_OK(file-&gt;Read(0, 9, &amp;read_res, buf));
  ASSERT_EQ(read_res.ToString(), &quot;ABXXXQQQQ&quot;);

  ASSERT_OK(file-&gt;Read(10, 3, &amp;read_res, buf));
  ASSERT_EQ(read_res.ToString(), &quot;ZYZ&quot;);

  ASSERT_OK(file-&gt;Read(200, 9, &amp;read_res, buf));
  ASSERT_EQ(read_res.ToString(), &quot;FFFFFXXXX&quot;);

  ASSERT_OK(file-&gt;Write(4, &quot;TTTTTTTTTTTTTTTT&quot;));
  ASSERT_OK(file-&gt;Read(0, 10, &amp;read_res, buf));
  ASSERT_EQ(read_res.ToString(), &quot;ABXXTTTTTT&quot;);

  // Clean up
  env_-&gt;DeleteFile(path);
}

class RandomRWFileWithMirrorString {
 public:
  explicit RandomRWFileWithMirrorString(RandomRWFile* _file) : file_(_file) {}

  void Write(size_t offset, const std::string&amp; data) {
    // Write to mirror string
    StringWrite(offset, data);

    // Write to file
    Status s = file_-&gt;Write(offset, data);
    ASSERT_OK(s) &lt;&lt; s.ToString();
  }

  void Read(size_t offset = 0, size_t n = 1000000) {
    Slice str_res(nullptr, 0);
    if (offset &lt; file_mirror_.size()) {
      size_t str_res_sz = std::min(file_mirror_.size() - offset, n);
      str_res = Slice(file_mirror_.data() + offset, str_res_sz);
      StopSliceAtNull(&amp;str_res);
    }

    Slice file_res;
    Status s = file_-&gt;Read(offset, n, &amp;file_res, buf_);
    ASSERT_OK(s) &lt;&lt; s.ToString();
    StopSliceAtNull(&amp;file_res);

    ASSERT_EQ(str_res.ToString(), file_res.ToString()) &lt;&lt; offset &lt;&lt; &quot; &quot; &lt;&lt; n;
  }

  void SetFile(RandomRWFile* _file) { file_ = _file; }

 private:
  void StringWrite(size_t offset, const std::string&amp; src) {
    if (offset + src.size() &gt; file_mirror_.size()) {
      file_mirror_.resize(offset + src.size(), &#039;\0&#039;);
    }

    char* pos = const_cast&lt;char*&gt;(file_mirror_.data() + offset);
    memcpy(pos, src.data(), src.size());
  }

  void StopSliceAtNull(Slice* slc) {
    for (size_t i = 0; i &lt; slc-&gt;size(); i++) {
      if ((*slc)[i] == &#039;\0&#039;) {
        *slc = Slice(slc-&gt;data(), i);
        break;
      }
    }
  }

  char buf_[10000];
  RandomRWFile* file_;
  std::string file_mirror_;
};

TEST_P(EnvPosixTestWithParam, PosixRandomRWFileRandomized) {
  const std::string path = test::PerThreadDBPath(env_, &quot;random_rw_file_rand&quot;);
  env_-&gt;DeleteFile(path);

  std::unique_ptr&lt;RandomRWFile&gt; file;

#ifdef OS_LINUX
  // Cannot open non-existing file.
  ASSERT_NOK(env_-&gt;NewRandomRWFile(path, &amp;file, EnvOptions()));
#endif

  // Create the file using WriteableFile
  {
    std::unique_ptr&lt;WritableFile&gt; wf;
    ASSERT_OK(env_-&gt;NewWritableFile(path, &amp;wf, EnvOptions()));
  }

  ASSERT_OK(env_-&gt;NewRandomRWFile(path, &amp;file, EnvOptions()));
  RandomRWFileWithMirrorString file_with_mirror(file.get());

  Random rnd(301);
  std::string buf;
  for (int i = 0; i &lt; 10000; i++) {
    // Genrate random data
    test::RandomString(&amp;rnd, 10, &amp;buf);

    // Pick random offset for write
    size_t write_off = rnd.Next() % 1000;
    file_with_mirror.Write(write_off, buf);

    // Pick random offset for read
    size_t read_off = rnd.Next() % 1000;
    size_t read_sz = rnd.Next() % 20;
    file_with_mirror.Read(read_off, read_sz);

    if (i % 500 == 0) {
      // Reopen the file every 500 iters
      ASSERT_OK(env_-&gt;NewRandomRWFile(path, &amp;file, EnvOptions()));
      file_with_mirror.SetFile(file.get());
    }
  }

  // clean up
  env_-&gt;DeleteFile(path);
}

class TestEnv : public EnvWrapper {
  public:
    explicit TestEnv() : EnvWrapper(Env::Default()),
                close_count(0) { }

  class TestLogger : public Logger {
   public:
    using Logger::Logv;
    TestLogger(TestEnv* env_ptr) : Logger() { env = env_ptr; }
    ~TestLogger() override {
      if (!closed_) {
        CloseHelper();
      }
    }
    void Logv(const char* /*format*/, va_list /*ap*/) override{};

   protected:
    Status CloseImpl() override { return CloseHelper(); }

   private:
    Status CloseHelper() {
      env-&gt;CloseCountInc();;
      return Status::OK();
    }
    TestEnv* env;
  };

  void CloseCountInc() { close_count++; }

  int GetCloseCount() { return close_count; }

  Status NewLogger(const std::string&amp; /*fname*/,
                   std::shared_ptr&lt;Logger&gt;* result) override {
    result-&gt;reset(new TestLogger(this));
    return Status::OK();
  }

 private:
  int close_count;
};

class EnvTest : public testing::Test {};

TEST_F(EnvTest, Close) {
  TestEnv* env = new TestEnv();
  std::shared_ptr&lt;Logger&gt; logger;
  Status s;

  s = env-&gt;NewLogger(&quot;&quot;, &amp;logger);
  ASSERT_EQ(s, Status::OK());
  logger.get()-&gt;Close();
  ASSERT_EQ(env-&gt;GetCloseCount(), 1);
  // Call Close() again. CloseHelper() should not be called again
  logger.get()-&gt;Close();
  ASSERT_EQ(env-&gt;GetCloseCount(), 1);
  logger.reset();
  ASSERT_EQ(env-&gt;GetCloseCount(), 1);

  s = env-&gt;NewLogger(&quot;&quot;, &amp;logger);
  ASSERT_EQ(s, Status::OK());
  logger.reset();
  ASSERT_EQ(env-&gt;GetCloseCount(), 2);

  delete env;
}

INSTANTIATE_TEST_CASE_P(DefaultEnvWithoutDirectIO, EnvPosixTestWithParam,
                        ::testing::Values(std::pair&lt;Env*, bool&gt;(Env::Default(),
                                                                false)));
#if !defined(ROCKSDB_LITE)
INSTANTIATE_TEST_CASE_P(DefaultEnvWithDirectIO, EnvPosixTestWithParam,
                        ::testing::Values(std::pair&lt;Env*, bool&gt;(Env::Default(),
                                                                true)));
#endif  // !defined(ROCKSDB_LITE)

#if !defined(ROCKSDB_LITE) &amp;&amp; !defined(OS_WIN)
static std::unique_ptr&lt;Env&gt; chroot_env(
    NewChrootEnv(Env::Default(), test::TmpDir(Env::Default())));
INSTANTIATE_TEST_CASE_P(
    ChrootEnvWithoutDirectIO, EnvPosixTestWithParam,
    ::testing::Values(std::pair&lt;Env*, bool&gt;(chroot_env.get(), false)));
INSTANTIATE_TEST_CASE_P(
    ChrootEnvWithDirectIO, EnvPosixTestWithParam,
    ::testing::Values(std::pair&lt;Env*, bool&gt;(chroot_env.get(), true)));
#endif  // !defined(ROCKSDB_LITE) &amp;&amp; !defined(OS_WIN)

}  // namespace ROCKSDB_NAMESPACE

int main(int argc, char** argv) {
  ::testing::InitGoogleTest(&amp;argc, argv);
  return RUN_ALL_TESTS();
}
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